Editorial
Falling Coronary Heart Disease Rates
A Better Explanation?
Russell V. Luepker, MD, MS, FACC, FAHA
T
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he coronary heart disease (CHD) epidemic peaked in
the 1960s. Since that time, age-adjusted mortality has
declined steadily in the United States and many other industrialized countries.1 Hospitalization for CHD has also declined,
particularly in the past 2 decades with CHD severity decreasing as non–ST-segment–elevation myocardial infarctions
increased, indicating milder forms of CHD.1 Finally, lifestyle
factors and associated risk factors improved such as smoking, hypertension, and cholesterol.1 These changes and the
trends over time lead naturally to the question of causality. Are
changes in lifestyles, risk factors, or acute and chronic clinical
care playing roles in this evolving picture, and how does each
influence the desired outcomes? In this issue of Circulation,
the article by Mannsverk and colleagues2 in Norway provides
insights into the evolving cardiovascular disease epidemic.
The debate also affects the so-called epidemiological transition or the anticipated rise of chronic diseases, particularly
CHD, in developing countries.6
One reason for the challenges in understanding trends is
the lack of comprehensive high-quality data. Population data
before 1970 are extremely limited and of poor quality. Even
mortality can be a challenge because both the fact of death and
the cause of death are frequently misclassified.7 Hospitalized
morbidity rates are similarly weak depending on discharge
diagnoses from administrative data. These are influenced by
evolving diagnostic fashion, new technology, and reimbursement.8 Outpatient clinic morbidity is even more variable and
difficult to gather. Some suggest that “big data” from administrative data sets will answer these questions, but these data
are subject to misclassification and bias. Finally, limited data
are available on risk factor patterns and trends. The National
Health and Nutrition Examination Survey, initiated in the
1960s, uses a national sampling strategy, but the numbers in
subgroups are small and the methods have changed over time.9
Nonetheless, there have been numerous attempts to understand the magnitude, causes, and relative impact of primary
prevention, acute care, and secondary prevention on CHD.5
Cohort studies such as Framingham are used to describe the
impact of risk factor change on outcomes.10 Others have evaluated outcomes by using clinical trials or epidemiology data
to estimate the magnitude of effect of various changes.5 More
complex models such as IMPACT use modeling techniques
to include these many factors.11,12 This results in proportions
attributable to primary prevention or clinical care. The proportion varies by country with the Scandinavian countries finding public health approaches a dominant factor. Others have
found proportions closer to half allocated to each in both US
and Western European studies.13 All suffer from limits of data
on the population under study. They also lack information on
the incidence or first event most likely to be affected by primary prevention and other risk factors such as stress or socioeconomic status. Finally, few have recognized the central role
of out-of-hospital sudden death accounting for more than half
of all CHD mortality. Sudden death is frequently observed in
individuals who have no previous history of CHD.13
The article by Mannsverk and colleagues2 addresses many
of the weaknesses in previous studies. Direct population data
are collected over 15 years on all of the relevant parameters
needed to make estimates of contributions to the decline.
Particularly critical is the availability of incidence data and
sudden death data at the population level.
Norway is recognized for high standards of living and
quality of life according to studies by the United Nations.14
With universal health care and high-technology medicine
widely available, Mannsverk’s study provides information
Article see p 74
The underlying causes of the CHD epidemic are well studied.3 After World War II, there were major changes in health
habits. Returning war veterans kept their smoking habit and
women soon followed. A diet high in fats became prevalent.
Physical activity declined as labor-saving devices entered
work places and automobiles became the dominant form of
transportation. The resulting peak in CHD in the mid-1960s is
now well recognized.
More serious research into the causes of the decline began
in the 1970s, highlighted at the National Institutes of Health
conference in 1979 that “discovered” the declining mortality
from CHD.4 At that conference, numerous explanations from
cardiopulmonary resuscitation to Medicare were advanced,
but few data were available to understand the observations. In
subsequent years, a debate ensued with some favoring primary
prevention attributable to changes in lifestyle and risk factor
reduction. Others cited secondary prevention with associated
acute and chronic medical care. Most agree that many factors
played some role in the decline but dispute their relative contributions.5 The relative contributions are more than an intellectual exercise, because different prevention and treatment
approaches have implications for resources and health policy.
The opinions expressed in this article are not necessarily those of the
editors or of the American Heart Association.
From Division of Epidemiology and Community Health, University of
Minnesota, Minneapolis.
Correspondence to Russell V. Luepker, MD, MS, FACC, FAHA,
Division of Epidemiology and Community Health, University of
Minnesota, 1300 South Second St, Suite 300, Minneapolis, MN 554541015. E-mail [email protected]
(Circulation. 2016;133:8-11.
DOI: 10.1161/CIRCULATIONAHA.115.019862.)
© 2015 American Heart Association, Inc.
Circulation is available at http://circ.ahajournals.org
DOI: 10.1161/CIRCULATIONAHA.115.019862
8
Luepker Explaining Falling Coronary Heart Disease Rates 9
Figure 1. Deaths and age-adjusted death rates for
cardiovascular diseases, United States, 1979 to
2008. NIH indicates National Institutes of Health.
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relevant to similar settings. This study is able to link hospital, clinic, and death records with population surveillance
because all citizens have a single identification number. The
data are collected with standard methods and quality control.
The city of Tromsø is relatively compact and isolated with
little out migration. With the use of the 3 population surveys
(1994–1995, 2001–2002, 2007–2008), risk factors were measured in subjects ≥25 years, a total of 29 582 healthy men and
women. Follow-up to 2010 resulted in 375 064 person-years
of experience. These large numbers produce stable estimates
of variables.
The Tromsø study finds that age- and sex-adjusted incidence of total coronary disease decreased by 3% annually
over the 15 years of follow-up. The decrease was found
primarily in reductions in out-of-hospital sudden death and
hospitalized ST-segment–elevation myocardial infarction.
Reductions in serum cholesterol accounted for approximately one-third of the event decline, but decreases in
smoking, blood pressure, and heart rate and increased
physical activity all contributed. Interestingly, increases in
body mass index and diabetes mellitus were associated with
modest increases in disease outcomes. Overall, risk factors
accounted for 66% of the decline in incidence. These data
contain important lessons.
The United States has similarities and differences
from Norway. The Norwegians have the ability to collect
Figure 2. Minnesota CHD hospitalizations (ICD-9 code 410) for adults 35+ years. 95% confidence intervals. CHD indicates coronary heart
disease; and ICD-9, International Classification of Diseases, Ninth Revision.
10 Circulation January 5, 2016
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comprehensive data at all levels in a population. Universal
health care allows the Norwegians to make policy decisions
regarding the emphasis and allocation of resources. The
United States has a similar high-technology environment.
However, health disparities in CHD incidence and outcomes
add to the US burden.1 The focus of Scandinavia public health
approaches is best exemplified in Finland. The Finns were recognized in the 1950s to have among the highest CHD rates
in the world. This was associated with elevated levels of risk
factors.3 A focused public health program resulted in dramatic
reductions in cardiovascular risk factors and a parallel decline
in CHD morbidity and mortality.15,16
There have also been major changes in the United States,
however. As shown in Figure 1, CHD mortality has been falling steadily since 1979 and before. These changes average a
3% per year decline in the age-adjusted data. The result of
this observation is that the expected lifespan of American citizens is, on average, rising. A second observation in Figure 1 is
found in the bars representing absolute deaths. These were flat
for many years because cardiovascular diseases were pushed
to growing older populations. However, in the past decade, the
absolute number of deaths has also been falling ≈3% per year.
As found in Norway, this suggests that the incidence of CHD
and sudden death is declining in the United States. One might
speculate as to the reasons for these declines, and there are
many postulated contenders, but in the United States there are
few data to answer the question. Information from the Centers
for Disease Control and Prevention in their National Health
and Nutrition Examination Survey surveys are not of adequate
size to address these trends. And these data are not linked to
morbidity information from clinic visits and hospitalizations.
This renders the analyses ecological where subjects cannot
be connected to individual health characteristics and disease
outcomes.
There are suggestions that big data can solve this problem. The enormous amounts of patient data contained in
private insurance, Medicare, and other registers are cited
as a unique opportunity to gather low-cost information.
However, these data are collected for billing and other
administrative purposes and frequently lack the quality
to draw scientific inferences. There is also the continuing
problem of linking of different data sets with individuals,
their care, and outcomes in a multisource healthcare system.
The direction of US trends is also evident in Figure 2. This
figure depicts trends in CHD hospitalizations in the state of
Minnesota. Hospitalizations with CHD discharge codes have
steadily fallen ≈3% per year in the past decade. This figure
contains incidence (new cases) admissions, recurrent cases
(same patient/same year), and the admissions among those
who were previously diagnosed. Further analyses of these
data find the falling trend of ST-segment–elevation myocardial infarction with a more modest falling trend in non–STsegment–elevation myocardial infarction.
The American Heart Association’s Annual Heart Disease
and Stroke Statistics Update is the most comprehensive source
of annual estimates of incidence, prevalence, and risk factor
distribution of the country.17 It is a carefully collated report
from many federal and private sources of varying designs,
populations, and sample sizes. It is the best data that we have.
However, it is neither nationally representative nor able to provide incidence data on CHD. As it stands, it is only an estimate
of important trends. Public health goals targeting the improvement in CHD outcomes include the Millions Heart Initiative,
American Heart Association 2020 goals, and the Healthy People
2020 goals. With the current systems, it will not be possible to
rigorously evaluate the outcomes of these recommendations.18
In 2011, The Institute of Medicine reports recommended
that a national surveillance program be established funded by
the Affordable Care Act. At present, there is no national surveillance effort to understand the origin of trends occurring in
the United States.18,19
The Norwegian experience demonstrates that high-quality
data can be collected in a population and inferences made regarding the roles of public health and medical interventions in population disease outcomes. The need to plan policy and allocate
resources, always present, is more imperative because the rising
costs for care of the chronically ill are becoming unsustainable
and much of the potential for prevention is, as yet, unrealized.
Sources of Funding
This work was supported by the National Heart, Lung, and Blood
Institute titled: Minnesota Heart Survey (grant R01-HL023727).
Disclosures
None.
References
1. National Institutes of Health. National Heart, Lung, and Blood Institute.
Morbidity & Mortality: 2012 Chart Book on Cardiovascular, Lung, and
Blood Diseases. www.nhlbi.nih.gov/files/docs/research/2012_ChartBook.
pdf. Accessed November 3, 2015.
2. Mannsverk J, Wilsgaard T, Mathiesen EB, Løchen ML, Rasmussen K,
Thelle DS, Njølstad, I. Hopstock LA, Bønaa, KH. Trends in modifiable
risk factors are associated with declining incidence of hospitalized and
nonhospitalized acute coronary heart disease in a population. Circulation.
2016;133:74–81. doi: 10.1161/CIRCULATIONAHA.115.016960.
3. Keys A. Seven Countries: A Multivariate Analysis of Death and Coronary
Heart Disease. Cambridge, MA: Harvard University Press; 1980.
4. Havlik RJ, Feinleib M. Proceedings of the Conference on the Decline in
Coronary Heart Disease Mortality. Bethesda, MD: National Heart, Lung
and Blood Institute, US Public Health Services, National Institutes of
Health; 1979. NIH publication 79–1610.
5. Jones DS, Greene JA. The contributions of prevention and treatment to the
decline in cardiovascular mortality: lessons from a forty-year debate. Health
Aff (Millwood). 2012;31:2250–2258. doi: 10.1377/hlthaff.2011.0639.
6. Yusuf S, Reddy S, Ounpuu S, Anand S. Global burden of cardiovascular
diseases: part I: general considerations, the epidemiologic transition, risk
factors, and impact of urbanization. Circulation. 2001;104:2746–2753.
7. Mikkelsen L, Phillips DE, AbouZahr C, Setel PW, de Savigny D, Lozano
R, Lopez AD. A global assessment of civil registration and vital statistics
systems: monitoring data quality and progress. Lancet. 2015;386:1395–
1406. doi: 10.1016/S0140-6736(15)60171-4.
8. Assaf AR, Lapane KL, McKenney JL, Carleton RA. Possible influence
of the prospective payment system on the assignment of discharge diagnoses for coronary heart disease. N Engl J Med. 1993;329:931–935. doi:
10.1056/NEJM199309233291307.
9. National Health and Nutrition Examination Survey - Official Site. www.
cdc.gov/nchs/nhanes/about_nhanes.htm. Accessed November 5, 2015.
10. Beaglehole R, LaRosa JC, Heiss G, Davis CE, Williams OD, Tyroler HA,
Rifkind BM. Serum cholesterol, diet, and the decline in coronary heart
disease mortality. Prev Med. 1979;8:538–547.
11.Capewell S, Morrison CE, McMurray JJ. Contribution of modern cardiovascular treatment and risk factor changes to the decline in coronary
heart disease mortality in Scotland between 1975 and 1994. Heart.
1999;81:380–386.
Luepker Explaining Falling Coronary Heart Disease Rates 11
12. Ford ES, Ajani UA, Croft JB, Critchley JA, Labarthe DR, Kottke TE,
Giles WH, Capewell S. Explaining the decrease in U.S. deaths from
coronary disease, 1980-2000. N Engl J Med. 2007;356:2388–2398. doi:
10.1056/NEJMsa053935.
13. Adabag AS, Peterson G, Apple FS, Titus J, King R, Luepker RV. Etiology
of sudden death in the community: results of anatomical, metabolic,
and genetic evaluation. Am Heart J. 2010;159:33–39. doi: 10.1016/j.
ahj.2009.10.019.
14. The World Post. A Partnership of the Huffington Post and Berggruen
Institute. Norway Best Place to Live: UN Report. http://www.
Huffingtonpost.com/2009/10/05norway-best-place-live_n_309698.html.
Accessed November 2, 2015.
15. Borodulin K, Vartiainen E, Peltonen M, Jousilahti P, Juolevi A, Laatikainen
T, Männistö S, Salomaa V, Sundvall J, Puska P. Forty-year trends in cardiovascular risk factors in Finland. Eur J Public Health. 2015;25:539–
546. doi: 10.1093/eurpub/cku174.
16.Dégano IR, Salomaa V, Veronesi G, Ferriéres J, Kirchberger I, Laks
T, Havulinna AS, Ruidavets JB, Ferrario MM, Meisinger C, Elosua R,
Marrugat J; Acute Myocardial Infarction Trends in Europe (AMITIE)
Study Investigators. Twenty-five-year trends in myocardial infarction
attack and mortality rates, and case-fatality, in six European populations.
Heart. 2015;101:1413–1421. doi: 10.1136/heartjnl-2014-307310.
17. Mozaffarian D, Benjamin EJ, Go AS, Arnett DK, Blaha MJ, Cushman
M, de Ferranti S, Després JP, Fullerton HJ, Howard VJ, Huffman MD,
Judd SE, Kissela BM, Lackland DT, Lichtman JH, Lisabeth LD, Liu
S, Mackey RH, Matchar DB, McGuire DK, Mohler ER 3rd, Moy CS,
Muntner P, Mussolino ME, Nasir K, Neumar RW, Nichol G, Palaniappan
L, Pandey DK, Reeves MJ, Rodriguez CJ, Sorlie PD, Stein J, Towfighi
A, Turan TN, Virani SS, Willey JZ, Woo D, Yeh RW, Turner MB;
American Heart Association Statistics Committee and Stroke Statistics
Subcommittee. Heart disease and stroke statistics–2015 update: a report
from the American Heart Association. Circulation. 2015;131:e29–e322.
doi: 10.1161/CIR.0000000000000152.
18. Committee on a National Surveillance System for Cardiovascular and
Select Chronic Diseases; Institute of Medicine of the National Academies.
A Nationwide Framework for Surveillance of Cardiovascular and Lung
Diseases. Washington, DC: The National Academics Press; 2011.
19.Sidney S, Rosamond WD, Howard VJ, Luepker RV; National Forum
for Heart Disease and Stroke Prevention. The “heart disease and
stroke statistics–2013 update” and the need for a national cardiovascular surveillance system. Circulation. 2013;127:21–23. doi: 10.1161/
CIRCULATIONAHA.112.155911.
Key Words: Editorials ◼ coronary heart disease ◼ death, sudden, cardiac
◼ epidemiology ◼ incidence ◼ morbidity ◼ mortality
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Falling Coronary Heart Disease Rates: A Better Explanation?
Russell V. Luepker
Circulation. 2016;133:8-11; originally published online November 18, 2015;
doi: 10.1161/CIRCULATIONAHA.115.019862
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